1. Field of Invention
The present invention relates to a technology of forming a bipolar junction transistor (BJT) and n-type and p-type metal-semiconductor field effect transistors (MESFETs) concurrently as a planar structure on the same gallium nitride (GaN) crystal growth layer.
2. Related Art
As shown in FIG. 1, a conventional planar structured gallium nitride (GaN) bipolar junction transistor (BJT) comprises a semi-insulating substrate for crystal growth 107, a collector layer 103, a base layer 102, a collector metal electrode 105, a base metal electrode 106, a GaN emitter region 101 and a collector contact well region 104 of an n-type GaN inverted from a p-type GaN formed by ion implantation or impurity diffusion technology. Generally, the provision of the planar structure of the GaN BJT has the advantage that another device may be fabricated and thus combined with the GaN BJT on the same horizontal base. Meanwhile, the GaN material can be prevented from a high contact resistance of the base metal after a dry etching process is applied thereto.